System degeneration of the thalamus. A clinico-neuropathological study.

A case of essential degeneration of the thalamus is reported. The patient was a 43-year-old Japanese male, who, a few weeks after mild head trauma, suffered from forgetfulness, psychomotor slowing, and Korsakoff's syndrome. Four to five months later, there were optical hallucinations and delirium and he died 19 months after the onset of symptoms. Neuropathological examination revealed symmetrical thalamic degeneration, whose distribution corresponded to phylogenetically younger subunits of the thalamus. In addition, there was olivovermian degeneration. These findings are identical to those of eleven cases hitherto reported. Five of these were Japanese, including the present one. The syndrome thalamic degeneration may now be classified as a special type of "system degeneration".